when a build fails with debian source

[Matt Garman <garman@netins.net>]

If I'm building a package from the Debian package source, and the build
fails half way through, how do I pick up where I left off when I retry,
rather than starting from scratch?

For example, I'm building xfree 3.3.5 from the Debian source.  Compiling
xfree86 takes a tremendous amount of time.  The build failed half-way
through because it couldn't find a header file.  I remedied the header
file situation, then again executed "./debian/rules binary" and the
build appears to be starting from the beginning!  That means I lost
hours of compile time already.  Was there something I should have done
to make it start where it left off, rather than start fresh?

I assumed debian/rules worked like make, i.e. it doesn't bother with
things that don't need to be changed.

Thanks,
Matt

-- 
Matt Garman, garman@ews.uiuc.edu
"And through the window in the wall
 Come streaming in on sunlight wings
 A million bright ambassadors of morning." 
	--Pink Floyd, "Echoes"